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  • CELLS  (6)
  • DIFFERENTIATION  (4)
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  • 1
    Keywords: APOPTOSIS ; CANCER ; CANCER CELLS ; CELLS ; EXPRESSION ; GROWTH ; IN-VITRO ; INHIBITOR ; proliferation ; tumor ; CELL ; CELL-PROLIFERATION ; Germany ; DRUG ; DIFFERENTIATION ; INDUCTION ; ACID ; NERVOUS-SYSTEM ; ASSAY ; CANCER-CELLS ; HISTONE DEACETYLASE ; histone deacetylase inhibitor ; p21(waf1) ; neuroblastoma ; INVITRO ; LEUKEMIA-CELLS ; ONCOLOGY ; CHILDHOOD ; RE ; medulloblastoma ; cell proliferation ; ASSAYS ; pharmacology ; USA ; anticancer drug ; childhood cancer ; HELMINTHOSPORIUM-CARBONUM (HC)-TOXIN ; HKI46F08
    Abstract: Embryonic childhood cancer such as neuroblastoma and medulloblastoma are still a therapeutic challenge requiring novel treatment approaches. Here, we investigated the antitumoral effects of HKI 46F08, a novel trifluoromethyl ketone histone deacetylase (HDAC) inhibitor with a nonhydroxamic acid type structure. HKI 46F08 inhibits in-vitro HDAC activity in cell-free assays with a half maximal inhibitory concentration of 0.6 mu mol/l and intracellular HDAC activity with a half maximal inhibitory concentration of 1.8 mu mol/l. The compound reduces viability of both cultured neuroblastoma and medulloblastoma cells with an EC50 of 0.1-4 mu mol/l. HKI 461708 efficiently arrests tumor cell proliferation, represses clonogenic growth and induces differentiation and apoptosis in both MYCN-amplified and nonamplified neuroblastoma cells. In summary, we identified HKI 48F08 as a structural novel, potent HDAC inhibitor with strong antitumoral activity against embryonic childhood cancer cells in the low micromolar range
    Type of Publication: Journal article published
    PubMed ID: 18765999
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  • 2
    Keywords: APOPTOSIS ; CANCER ; CELLS ; GROWTH ; INHIBITOR ; tumor ; CELL ; Germany ; IN-VIVO ; INHIBITION ; MODEL ; PATHWAY ; THERAPY ; DISEASE ; GENE ; GENES ; PROTEIN ; PROTEINS ; DRUG ; DIFFERENTIATION ; TUMORS ; NEUROBLASTOMA-CELLS ; ACTIVATION ; MECHANISM ; FAMILY ; prognosis ; mechanisms ; cell cycle ; CELL-CYCLE ; CYCLE ; MEMBERS ; SUSCEPTIBILITY ; ANTITUMOR-ACTIVITY ; MOUSE ; TRIAL ; TRIALS ; CELL-DEATH ; CLINICAL-TRIALS ; chemotherapy ; MOUSE MODEL ; TARGETS ; CHILDREN ; HDAC inhibitors ; HISTONE DEACETYLASE ; INTERFERON-ALPHA ; REPRESSION ; TRAIL-INDUCED APOPTOSIS ; neuroblastoma ; HDAC ; INHIBITORS ; ADULT ; review ; FAMILIES ; THERAPIES ; tumor suppressor gene ; EPIGENETICS ; CANCERS ; valproic acid ; Phase I ; SODIUM VALPROATE ; MALIGNANT PHENOTYPE ; NUCLEAR EXPORT ; drug targets ; DRUG-TARGET ; HDAC inhibitor
    Abstract: Histone deacetylases (HDACs) are an emerging class of novel anti-cancer drug targets. Recently, studies in adult cancers and in neuroblastoma have shown that individual HDAC family members are aberrantly expressed in tumors and correlate with disease stage and prognosis. In neuroblastoma, knockdown of individual HDAC family members causes distinct phenotypes ranging from differentiation to apoptosis. HDACs are involved in controlling MYCN function and are upregulated in chemotherapy-resistant neuroblastoma cells. Treatment with unselective pan-HDAC inhibitors causes cell cycle arrest, differentiation, apoptosis, and inhibition of clonogenic growth of neuroblastoma cells, and restores susceptibility to chemotherapy treatment. The molecular mechanisms mediating the anti-cancer effects of HDAC inhibitors on neuroblastoma cells are incompletely understood and involve targeting of aberrant epigenetic repression of tumor suppressor genes, activation of developmental differentiation pathways, as well as changing the acetylation level and function of non-histone proteins. In neuroblastoma mouse models, unselective HDAC inhibitors demonstrate antitumoral effects. First phase I clinical trials in children with refractory cancers using HDAC inhibitors depsipeptide and the recently approved vorinostat are underway. This review summarizes our current knowledge about classical HDAC family members as novel drug targets for neuroblastoma therapy and discusses the potential role of next generation, selective HDAC inhibitors
    Type of Publication: Journal article published
    PubMed ID: 19199971
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  • 3
    Keywords: CANCER ; CANCER CELLS ; CELLS ; INHIBITOR ; tumor ; CELL ; Germany ; PHASE-I ; THERAPY ; LUNG-CANCER ; DEATH ; DISEASE ; DISEASES ; GENE ; GENES ; DRUG ; TUMORS ; MICE ; MESSENGER-RNA EXPRESSION ; FAMILY ; MEMBERS ; BREAST-CANCER ; TRIAL ; TRIALS ; CLINICAL-TRIALS ; CANCER-CELLS ; TARGETS ; HDAC inhibitors ; HISTONE DEACETYLASE ; histone deacetylase inhibitor ; HDAC ; INHIBITORS ; SINGLE ; review ; FAMILIES ; IV ; CLASS-II ; development ; PHASE ; COMPOUND ; HYPOXIA-INDUCIBLE FACTOR-1-ALPHA ; REFRACTORY SOLID TUMORS ; VIVO ANTITUMOR-ACTIVITY ; drug targets ; DRUG-TARGET ; HDAC inhibitor ; CONTROLS CHONDROCYTE HYPERTROPHY
    Abstract: Histone deacetylases comprise a family of 18 genes, which are grouped into classes I-IV based on their homology to their respective yeast orthologues. Classes I, II, and IV consist of 11 family members, which are referred to as "classical" HDACs, whereas the 7 class III members are called sirtuins. Classical HDACs are a promising novel class of anti-cancer drug targets. First HDAC inhibitors have been evaluated in clinical trials and show activity against several cancer diseases. However, these compounds act unselectively against several or all 11 HDAC family members. As a consequence, clinical phase 1 trials document a wide range of side effects. Therefore, the current challenge in the field is to define the cancer relevant HDAC family member(s) in a given tumor type and to design selective inhibitors, which target cancer cells but leave out normal cells. Knockout of single HDAC family members in mice produces a variety of phenotypes ranging from early embryonic death to viable animals with only discrete alterations, indicating that potential side effects of HDAC inhibitors depend on the selectivity of the compounds. Recently, several studies have shown that certain HDAC family members are aberrantly expressed in several tumors and have non-redundant function in controlling hallmarks of cancer cells. The aim of this review is to discuss individual HDAC family members as drug targets in cancer taking into consideration their function under physiological conditions and their oncogenic potential in malignant disease. (C) 2008 Elsevier Ireland Ltd. All rights reserved
    Type of Publication: Journal article published
    PubMed ID: 18824292
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  • 4
    Keywords: DIFFERENTIATION ; PROGNOSTIC-SIGNIFICANCE ; CENTRAL-NERVOUS-SYSTEM ; EMBRYONIC STEM-CELLS ; BRAIN-TUMORS ; intermediate filament protein ; CHILDHOOD EPENDYMOMAS ; PEDIATRIC INTRACRANIAL EPENDYMOMAS ; DIFFERENT TUMORS ; MARKER NESTIN
    Abstract: Ependymomas are primary brain tumors found throughout the central nervous system (CNS) in children and adults. Currently, many treatment protocols stratify grade I and II ependymomas as low-risk tumors, whereas grade III anaplastic ependymomas are considered high-risk tumors. The prognostic significance of World Health Organization (WHO) grade II or III, however, remains debated, and it is furthermore increasingly recognized that the pathologic differentiation between grades II and III is arbitrary in daily practice, thus resulting in imprecise risk stratification. Therefore, prognostic markers enabling more precise stratification to guide treatment decisions are urgently needed. An analysis of n = 379 tumor samples revealed that protein expression of nestin, a marker for neural stem and progenitor cells established as a routine staining in most neuropathology centers, is associated with poor outcome in intracranial ependymomas. Most importantly, nestin-positive grade II ependymomas have the same prognosis as grade III ependymomas. Multivariable analysis demonstrates that nestin positivity is an independent marker for poor progression-free survival (PFS) and overall survival (OS). Gene expression analysis for transcriptionally co-regulated genes revealed a strong association of developmental and epigenetic processes with nestin. In summary, our data implicate nestin as a useful novel marker for intracranial ependymoma risk stratification easily implementable in routine diagnostics.
    Type of Publication: Journal article published
    PubMed ID: 22568867
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  • 5
    Keywords: EXPRESSION ; GENE ; DIFFERENTIATION ; IDENTIFICATION ; EMBRYONIC STEM-CELLS ; HYPERMETHYLATION ; SUPPRESSOR ; methylome ; CANCER GENOME ; CPG ISLAND SHORES
    Abstract: Epigenetic alterations, that is, disruption of DNA methylation and chromatin architecture, are now acknowledged as a universal feature of tumorigenesis. Medulloblastoma, a clinically challenging, malignant childhood brain tumour, is no exception. Despite much progress from recent genomics studies, with recurrent changes identified in each of the four distinct tumour subgroups (WNT-pathway-activated, SHH-pathway-activated, and the less-well-characterized Group 3 and Group 4), many cases still lack an obvious genetic driver. Here we present whole-genome bisulphite-sequencing data from thirty-four human and five murine tumours plus eight human and three murine normal controls, augmented with matched whole-genome, RNA and chromatin immunoprecipitation sequencing data. This comprehensive data set allowed us to decipher several features underlying the interplay between the genome, epigenome and transcriptome, and its effects on medulloblastoma pathophysiology. Most notable were highly prevalent regions of hypomethylation correlating with increased gene expression, extending tens of kilobases downstream of transcription start sites. Focal regions of low methylation linked to transcription-factor-binding sites shed light on differential transcriptional networks between subgroups, whereas increased methylation due to re-normalization of repressed chromatin in DNA methylation valleys was positively correlated with gene expression. Large, partially methylated domains affecting up to one-third of the genome showed increased mutation rates and gene silencing in a subgroup-specific fashion. Epigenetic alterations also affected novel medulloblastoma candidate genes (for example, LIN28B), resulting in alternative promoter usage and/or differential messenger RNA/microRNA expression. Analysis of mouse medulloblastoma and precursor-cell methylation demonstrated a somatic origin for many alterations. Our data provide insights into the epigenetic regulation of transcription and genome organization in medulloblastoma pathogenesis, which are probably also of importance in a wider developmental and disease context.
    Type of Publication: Journal article published
    PubMed ID: 24847876
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  • 6
    Keywords: CANCER ; CELLS ; EXPRESSION ; GENE ; transcription ; CREB ; acetylation ; HISTONE DEACETYLASE INHIBITORS ; SOX4 ; COOPERATE
    Abstract: For differentiation-defective malignancies, compounds that modulate transcription, such as retinoic acid and histone deacetylase (HDAC) inhibitors, are of particular interest. HDAC inhibitors are currently under investigation for the treatment of a broad spectrum of cancer diseases. However, one clinical drawback is class-specific toxicity of unselective inhibitors, limiting their full anticancer potential. Selective targeting of individual HDAC isozymes in defined tumor entities may therefore be an attractive alternative treatment approach. We have previously identified HDAC family member 8 (HDAC8) as a novel target in childhood neuroblastoma. Using small-molecule inhibitors, we now demonstrate that selective inhibition of HDAC8 exhibits antineuroblastoma activity without toxicity in two xenograft mouse models of MYCN oncogene-amplified neuroblastoma. In contrast, the unselective HDAC inhibitor vorinostat was more toxic in the same models. HDAC8-selective inhibition induced cell cycle arrest and differentiation in vitro and in vivo. Upon combination with retinoic acid, differentiation was significantly enhanced, as demonstrated by elongated neurofilament-positive neurites and upregulation of NTRK1. Additionally, MYCN oncogene expression was downregulated in vitro and tumor cell growth was markedly reduced in vivo. Mechanistic studies suggest that cAMP-response element-binding protein (CREB) links HDAC8- and retinoic acid-mediated gene transcription. In conclusion, HDAC-selective targeting can be effective in tumors exhibiting HDAC isozyme-dependent tumor growth in vivo and can be combined with differentiation-inducing agents.
    Type of Publication: Journal article published
    PubMed ID: 25695609
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  • 7
    Keywords: CELLS ; HYBRIDIZATION ; TUMORS ; MESSENGER-RNA ; IDENTIFICATION ; CENTRAL-NERVOUS-SYSTEM ; CHROMOSOMAL IMBALANCES ; CHILDHOOD ; NEURONAL DIFFERENTIATION ; INTRACRANIAL EPENDYMOMAS
    Abstract: Nonresectable ependymomas are associated with poor prognosis despite intensive radiochemotherapy and radiation. The molecular pathogenesis of ependymoma initiation and progression is largely unknown. We here present a case of therapy-refractory, progressive ependymoma with cerebrospinal as well as extraneural metastases, which allowed us for the first time to follow the stepwise accumulation of chromosome aberrations during disease progression. Genome-wide DNA copy-number analysis showed sequential deletions on chromosomes 1, 9, and 14 as well as a homozygous deletion of the CDKN2A locus, underscoring its role in tumor progression. Gradual loss at Ip36 was associated with loss of protein expression of the putative tumor suppressor gene AJAPI/SHREWI. In summary, this is the first report on acquired genomic aberrations in ependymoma over time pointing to novel candidate tumor suppressor genes. This analysis provides molecular insights into the chronology of genetic events in this case from initial localized tumor to widespread metastasized disease.
    Type of Publication: Journal article published
    PubMed ID: 19025795
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  • 8
    Keywords: CELLS ; GENES ; CHROMATIN ; DNA methylation ; BRAIN-TUMORS ; HIGH-GRADE GLIOMAS ; INTRINSIC PONTINE GLIOMAS ; COPY-NUMBER ABERRATIONS ; ONCOMETABOLITE 2-HYDROXYGLUTARATE ; HISTONE H3.3
    Abstract: Glioblastoma (GBM) is a brain tumor that carries a dismal prognosis and displays considerable heterogeneity. We have recently identified recurrent H3F3A mutations affecting two critical amino acids (K27 and G34) of histone H3.3 in one-third of pediatric GBM. Here, we show that each H3F3A mutation defines an epigenetic subgroup of GBM with a distinct global methylation pattern, and that they are mutually exclusive with IDH1 mutations, which characterize a third mutation-defined subgroup. Three further epigenetic subgroups were enriched for hallmark genetic events of adult GBM and/or established transcriptomic signatures. We also demonstrate that the two H3F3A mutations give rise to GBMs in separate anatomic compartments, with differential regulation of transcription factors OLIG1, OLIG2, and FOXG1, possibly reflecting different cellular origins.
    Type of Publication: Journal article published
    PubMed ID: 23079654
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